This invention relates to an ultrasonic motor for use in a timepiece, etc., and to an electronic appliance using the same.
Recently, ultrasonic motors featured by small size and light weight have been used in small-sized precision appliances, such as timepieces.
The conventional ultrasonic motor 100 is structured as shown in a structural block diagram (FIG. 4) and perspective view (FIG. 5), such that on a support plate 102, a piezoelectric element 103 is provided, and a vibration member 104 is joined to the piezoelectric element 103, a moving member 105 is rotatably rested on projections 104a, 104a of the vibration member 104, a pressurizing means 106 urges the moving member 105 in pressure contact with the moving member 104, and a connection circuit means 107 is provided for electrical connection.
This ultrasonic motor 100 has been built in an electronic appliance, together with a separately fabricated drive circuit (driving driver 109, externally attached part 110) 108, adjusting capacitor 111, control circuit 112 and power source 113.
The ultrasonic motor 100 has been configured so that a current given from the power source 113 is converted into a required alternating current by the drive circuit 108 and the adjusting capacitor 111, thereby being driven by the supply of alternating current under control of the control circuit 112.
In such a case, the current which is to be converted into an alternating current and supplied by the power source 113 to the driving driver 109 has been corrected for being adapted to a phase characteristic of a motor drive section of the ultrasonic motor 100 by adjustment in capacitance of the adjusting capacitor 111.
In the conventional device, however, the drive circuit 108 has been fabricated separately from the ultrasonic motor 100 as described above. consequently, after manufacture the adjusting capacitor 111 in a stage of mutual connection is required to be changed in capacitance so that the phase of the alternating current supplied through the drive circuit 108 is adapted to a phase characteristic of the motor drive section of the ultrasonic motor 100.
Due to this, phase characteristic errors in the motor drive section of an individual ultrasonic motor 100 and phase characteristic errors in an individual drive circuit 108 have to be corrected by the capacitance adjustment of the adjusting capacitor 111, when assembled onto an electronic appliance, replaced, repaired or so. Thus, it is difficult for the ultrasonic motor 100 to be repaired or replaced.
Even in a case that repairing is done by a knowledgeable technician, the ultrasonic motor 100 and the drive circuit 108 require separate preparation and adjustment, thus raising repair cost. This is true for a manufacturing process for an electronic appliance built with such an ultrasonic motor 100, also raising manufacture cost therefor.
Also, despite the fact that the ultrasonic motor 100 is small in size, the increase in size of the separately-fabricated drive circuit 108 also results in an increase in size of an electronic appliance to be built with the same.
Also, the ultrasonic motor 100 and the drive circuit 108 if separated would make assembly troublesome due to an adjustment operation besides increasing the number of assembly operation processes for incorporating them into an electronic appliance, resulting in the increase of manufacturing cost.
Also, in the conventional ultrasonic motor 100, the support plate 102 has been made of metal so that the same support plate 102 is connected as an electrode to a circuit board of an electronic appliance to be built with the ultrasonic motor 100. Accordingly, there has been a necessity of providing on the support plate 102 an insulator for providing a connection circuit means 107 thus making the manufacture complicated. Also, where incorporating the ultrasonic motor 100 in an electronic appliance, wiring connection should be necessarily secured between the electronic appliance circuit board and the support plate 102, thus lowering design freedom.
It is a first object of this invention to provide an ultrasonic motor which is compact and easy to handle but facilitates incorporation in an electronic appliance or the like or to repair. It is a second object to provide an electronic appliance provided with this ultrasonic motor.
In order to solve the above problem, an ultrasonic motor according to one aspect of the invention is an ultrasonic motor having a piezoelectric element to undergo expansive-and-contractive movement due to application of alternating current, a vibration member to be vibrated by the expansive-and-contractive movement of the piezoelectric element, a moving member to be driven by the vibration of the vibration member, and a connection circuit means for electrical connection, the ultrasonic motor characterized in that a drive circuit for converting a current from a power source into a required alternating current to be supplied to an ultrasonic motor drive section is provided in the connection circuit means.
According to the invention, because the connection circuit means is structurally provided with the drive circuit, the ultrasonic motor is a single unit including the drive circuit.
Accordingly, it is possible to build, or replace, as a compact and easy-handled single unit including the drive circuit in an electronic appliance, facilitating incorporation or replacement and repair.
An ultrasonic motor according to another aspect has the connection circuit means provided with a phase adjusting section to adjust phase characteristics of the ultrasonic motor drive section and the drive circuit.
According to the invention, because the ultrasonic motor is provided with the phase adjusting section in the connection circuit means, the phase characteristic of the ultrasonic motor drive section and drive circuit can be easily adjusted by the phase adjusting section during manufacturing and assembling the ultrasonic motor.
Consequently, after manufacture, there is no need for conducting adjustment again upon assembling into an electronic appliance or during replacement, thus facilitating assembling into an electronic appliance or repair.
Consequently, after manufacture, there is no need for conducting the adjustment again upon assembling into an electronic appliance or during replacement, thus facilitating assembling into an electronic appliance or repair.
An ultrasonic motor according another aspect of the invention is an ultrasonic motor wherein the connection circuit means are provided integral with the support plate. According to this aspect of the invention, the connection circuit means is provided integral with the support plate, and the connection circuit means and the support plate can be handled as a single part. The ultrasonic motor during manufacture is easy to handle, reducing the manufacture process and relieving manufacturing labor.
The invention according to another aspect is an electronic appliance, and is characterized by being provided with an ultrasonic motor according to any one of the foregoing aspects.
As above, according to the invention of the foregoing aspect, the electronic appliance has an ultrasonic motor that is easy to assemble, replace or repair.